These People’s Challenge team reports have a different purpose, which is to provide our CrowdJustice supporters with a concise insider’s overview of how the arguments are developing and the Court’s reaction.

Lord Neuberger opened the hearing by making an Order to protect the identities of some of the parties (the AB children and carers) and address information relating to others, including the People’s Challenge group. He explained:

“We have made this order largely because various individuals have received threats of serious violence and unpleasant abuse in emails and other electronic communications. Threatening and abusing people because they are exercising their fundamental right to go to court undermines the rule of law. Anyone who communicates such threats or abuse should be aware that there are legal powers designed to ensure that access to the courts is available to everybody.”

He then welcomed those present in court and watching on line, acknowledging the public interest, but emphasising that the “wider political questions” surrounding Brexit were “not the subject of this appeal”. Rather it concerned: “legal issues and, as judges, our duty is to consider those issues impartially and decide the case according to law”. Every party to the case had accepted the 11 Justices were impartial and should not recuse themselves, he noted.

These themes were picked up in the opening of the Government’s case by the Attorney General, Jeremy Wright QC, who acknowledged the claim concerned “a clear question of law” that had been “properly bought” to court for determination. This marked a significant, and welcome, shift from the position taken by the Prime Minister some months ago.

Mr Wright then gave an outline of the Government’s case. There had been an electoral commitment to hold a referendum and to implement the result. The product was the 2015 EU Referendum Act, and a majority of those voting had voted to leave, something the Divisional Court had treated as “legally irrelevant” when concluding the prerogative could not be used to bring about departure. It has been wrong to do so, he argued. There were “legitimate public expectations” to consider.

As to the prerogative, he said, this as not an ancient relic, but a contemporary legal necessity “essential to the effective conduct of public business” in a dualist system of law (where international legal obligations between states and those enforceable by citizens are separate). The prerogative “operates wholly in accordance with parliamentary sovereignty” because Parliament understands its utility, but will limit it when appropriate, albeit “sparingly”. This was a matter of practicality too:

“The need for the Government to maintain control over strategy, policy and operational matters in conducting our bilateral or multilateral international relationships is, we say, clear and compelling.”

Of course, none of these statements of principle are an answer to the People’s Challenge case: that Parliament has legislated to grant citizenship rights that cannot be overridden by the prerogative.

On this, Mr Wright said that Parliament had positively chosen to control the prerogative in relation to treaty notification and ratification using the Constitutional Reform and Governance Act 2010, but only up to a point. The controls it introduced did not prevent the invocation of Article 50, so Parliament must have chosen not to control that. Other opportunities to legislate and introduce controls had not been seized.

This became a major theme of the Government’s case throughout the day. According to Mr Wright and Mr Eadie QCs, Parliament’s ‘silence’ on the use of the use of the prerogative to invoke Article 50 meant it remained sovereign, but that sovereignty was manifesting itself in passive, mute acquiescence to the Government’s use of prerogative power in this context.

The People’s Challenge has a clear, principled answer to this: the Government’s case has the wrong legal starting point. It must show the foreign relations prerogative allows it to take away citizens’ statutory rights in the first place. And it cannot.

Mr Wright went on to make the first novel point of the Government’s case. Parliament, he said:

“… passed the 2015 Act in the clear knowledge, and expectation, that the process by which the exit from the EU would take place was set out in Article 50 of the Treaty on European Union. It knew what would happen when that process was begun, and it took no step, made no provision, imposed no constraint, to prevent the Government giving notice to do so in the usual exercise of prerogative power.”

But no evidence has been produced that Parliament, or even the Government, intended that the prerogative would be used to implement the 2015 Act if a majority voted leave.

“I say Parliament can stand up for itself”, Mr Wright concluded. The exercise of its sovereignty to remain silent and not control the Government’s use of the prerogative should be “respected”.

James Eadie QC then rose to develop the Government’s appeal in detail. Unlike Mr Wright, he was frequently interrupted with penetrating questions, particularly from Lord Mance, Lord Sumption, Lord Carnwath and Lord Neuberger. Here are some highlights.

Opening his submissions, Mr Eadie descried the prerogative as “a power to act according to discretion for the public good” relying on the Burmah Oil case. “Suspicion of prerogative powers accompanied by judicial concern at their exercise” was misplaced. They are “essential”.

A “conduit” allowing “transposition” of the fruits of negotiations at international level into UK law was also needed, he said, but that was the real function of the European Communities Act 1972. It created no rights at all.

Mr Eadie then gave other examples of three other “conduit” statutes. Lord Mance asked:

“Does any of your three examples cater for a situation where the continued operation of domestic legal provisions is affected by whether or not the international position remains the same?”

Mr Eadie accepted none did. The 1972 Act was different in that sense.

Importantly, Lord Mance then asked whether a conduit statute could be used to take away rights completely, leaving none behind (i.e. the effect of invoking Article 50). Mr Eadie said that could happen. Other Justices questioned whether it really was his case that the substance of EU membership could be hollowed out in this way. Lord Mance explored the implications of Mr Eadie’s argument further:

“Mr Eadie, do you say that the European Communities Act 1972 was neutral as to whether the United Kingdom was a member of the European Communities?”

to which Mr Eadie gave this startling reply:

“We say it proceeded on the fundamental assumption that that ultimate decision on the international plane was a matter for Government.”

In other words, membership of the European Community and then the European Union has, for 40 years, been a Governmental decision, not a Parliamentary one. This was no slip – Mr Eadie went on to describe the 1972 Act, one of the most debated in recent history when at bill stage, in this way:

“Parliament was… merely facilitating the membership, should the Government, in the exercise of its treaty prerogative, take the United Kingdom into the EEC.”

Mr Eadie’s remaining submissions focussed on the 1920 De Keyser’s Royal Hotel case, which involved seizure of property in wartime, arguing that it established a principle that the prerogative was unrestricted unless Parliament had imposed control “expressly or by necessary implication.”

Picking up a point from the People’s Challenge Written Case, Lord Sumption said:

“You surely have to ask: what are the limits if any of the prerogative power to make and unmake treaties? If the position is that the prerogative power is only as broad as it is, because the assumption is being made that it does not alter domestic legal rights, then, you know, one may well arrive at a situation in which you just never get to the question of what the statute says, unless it is being suggested that it actually confers a prerogative right to change the law which would not otherwise exist.”

In other words, was the Government subsisting that the law of the land could be changed using the prerogative? Mr Eadie’s response was candid:

“Prerogative power in the field of making of treaties, ratification of treaties and withdrawal from treaties, is and always has been a general power, untrammelled by any such implication which can have… impacts into domestic law through any or all of the various models that we have analysed our in our cases.”

To sum up the Government’s case so far, then, prerogative power is “untrammelled”, the law of the land can be changed using it, Parliament was “merely” the facilitator of the exercise of that power when we joined the EEC and has now silently consented to its use to take away all UK citizens’ EU rights. There is something unsettlingly Orwellian about the Government’s case so far and there is nothing to suggest the Justices are persuaded.

Mr Eadie’s submissions continue this morning, before he hands over to Lord Keen QC, the Advocate General for Scotland, and John F Larkin QC, Attorney General for Northern Ireland. Both support the Government and will argue against the devolution arguments put by the Scottish and Welsh Governments and the Northern Irish appellants.